Use if constexpr () in public headers

Use if constexpr() for conditions that are constexpr. This
fixes MSVC warning C4127, which is enabled for compiler warning
level 4 (/W4).

While at it, don't narrow down the type from size_t to
quint32.

Change-Id: I95403e5d60173ed48478532dcdcc09ecd666fbe0
Reviewed-by: Marc Mutz <marc.mutz@qt.io>
(cherry picked from commit 37df21126dcf94bb5aaaa8f1e41cf458630be86d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 9 insertions, 7 deletions

diff --git a/src/serialbus/qmodbuspdu.h b/src/serialbus/qmodbuspdu.h
index 7a2e46c..61ea3a7 100644
--- a/src/serialbus/qmodbuspdu.h
+++ b/src/serialbus/qmodbuspdu.h
@@ -133,19 +133,21 @@ private:
 
     template<typename ... Args> void encode(Args ... newData) {
         m_data.clear();
-        Q_CONSTEXPR quint32 argCount = sizeof...(Args);
-        if (argCount > 0) {
+        constexpr size_t argCount = sizeof...(Args);
+        if constexpr (argCount > 0) {
             QDataStream stream(&m_data, QIODevice::WriteOnly);
             char tmp[argCount] = { (encode(&stream, newData), void(), '0')... };
             Q_UNUSED(tmp);
         }
     }
     template<typename ... Args> void decode(Args ... newData) const {
-        Q_CONSTEXPR quint32 argCount = sizeof...(Args);
-        if (argCount > 0 && !m_data.isEmpty()) {
-            QDataStream stream(m_data);
-            char tmp[argCount] = { (decode(&stream, newData), void(), '0')... };
-            Q_UNUSED(tmp);
+        constexpr size_t argCount = sizeof...(Args);
+        if constexpr (argCount > 0) {
+            if (!m_data.isEmpty()) {
+                QDataStream stream(m_data);
+                char tmp[argCount] = { (decode(&stream, newData), void(), '0')... };
+                Q_UNUSED(tmp);
+            }
         }
     }